Ferroelectric liquid crystal compounds having perfluoroether terminal portions

Abstract

Fluorine-containing liquid crystal compounds are provided. The compounds comprise a fluorocarbon terminal portion having at least one catenary ether oxygen and a hydrocarbon terminal portion, the terminal portion being connected by a central core, the compounds having smectic mesophases or having latent smectic mesophases.

What is claimed is: 
     
       1. An achiral fluorine-containing liquid crystal compound of the general formula I: ##STR45## where M, N, and P are each independently ##STR46## a, b, and c are each independently zero or an integer of from 1 to 3 with the proviso that the sum of a+b+c be at least 2; each A and B are non-directionally and independently a covalent bond, ##STR47## each X, Y, and Z are independently --H, --Cl, --F, --Br, --I, --OH, --OCH 3 , --CN, or --NO 2  ;   each 1, m, and n are independently zero or an integer of 1 to 4, D is ##STR48##  and q and q' are independently 1 to 20, and R can be straight chain or branched; and   R f  is (C x  F 2x  O) z  C y  F 2y+1  where x is independently 1 to 10 for each C x  F 2x  O group, y is 1 to 10 and z is 1 to 6.   
     
     
       2. A compound according to claim 1 wherein said compound can be represented by the formula ##STR49## where d is 5 to 10, x is independently 1 to 3 for each C x  F 2x  O group, y is 1 to 4 and z is 1 to 3. 
     
     
       3. A compound according to claim 1 wherein said compound can be represented by the formula ##STR50## where t is 6, 8 or 10. 
     
     
       4. A compound according to claim 1 wherein said compound can be represented by the formula ##STR51## where t is 6, 8 or 10. 
     
     
       5. A compound according to claim 1 wherein said compound can be represented by the formula ##STR52## where t is 6, 8 or 10. 
     
     
       6. A compound according to claim 1 wherein said compound can be represented by the formula ##STR53## 
     
     
       7. A compound according to claim 1 wherein said compound can be represented by the formula ##STR54## where t is 6, 8 or 10. 
     
     
       8. A compound according to claim 1 wherein said compound can be represented by the formula ##STR55## where t is 6, 8 or 10. 
     
     
       9. A compound according to claim 1 wherein said compound can be represented by the formula ##STR56## 
     
     
       10. A compound according to claim 1 wherein said compound can be represented by the formula ##STR57## 
     
     
       11. A compound according to claim 1 wherein R f  is --CF 2  OCF 2  CF 2  OC 4  F 9 . 
     
     
       12. Liquid crystal mixtures comprising at least one compound according to claim 1 and at least one chiral liquid crystal compound, said chiral liquid crystal compound being present in an amount sufficient to provide the mixture with ferroelectric properties. 
     
     
       13. A liquid crystal display device containing said compound of claim 1 wherein said compound has a smectic mesophase.